Contingency management interventions are quite successful at initiating and maintaining clinically significant periods of abstinence. Typically, contingency management is delivered in conjunction with a psychosocial substance abuse treatment program. However, there has been scant attention directed towards how to maximally deliver the contingency management interventions as part of a larger treatment package. One issue that will be important is to determine what the optimal length of a contingency management intervention should be. This proposal describes an experimentally rigorous clinical trial designed to begin exploring this issue. Methamphetamine-dependent participants will be randomly assigned to one of four conditions: standard treatment (16 weeks of psychosocial treatment plus no contingency management), 1 month contingency management (16 weeks of psychosocial treatment with contingency management delivered during the first 4 weeks), 2 month contingency management (16 weeks of psychosocial treatment with contingency management delivered during the first 8 weeks), 4 month contingency management (16 weeks of psychosocial treatment with contingency management delivered during the entire 16 weeks). Data will be analyzed to determine if the different durations of contingency management produce different rates of initiation of abstinence or different patterns of maintenance of abstinence. Follow up data collection will be conducted for a one year period, starting at randomization, to determine if the different durations of contingency management inculcate longer periods of post-treatment abstinence or result in different patterns of relapse. The successful completion of the proposed project will serve several purposes. First, it will provide data that will be useful in determining what the optimal length of contingency management interventions should be. This will be useful as we begin to transfer the contingency management approaches into community-based treatment clinics. This may also help to contain the cost of delivering contingency management interventions if it is demonstrated that shorter durations of contingency management are as effective as longer durations. Secondly, the successful completion of the proposed research will provide additional information on the utility of treating methamphetamine dependence with contingency management. This is timely, given the burgeoning rates of methamphetamine abuse being reported.